Dan Magenheimer
2011-Sep-24 20:58 UTC
[Xen-devel] [PATCH] xen: Fix selfballooning and ensure it doesn''t go too far
[PATCH] xen: Fix selfballooning and ensure it doesn''t go too far The balloon driver''s "current_pages" is very different from totalram_pages. Self-ballooning needs to be driven by the latter. Also, Committed_AS doesn''t account for pages used by the kernel so enforce a floor for when there are little or no user-space threads using memory. Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> diff --git a/drivers/xen/xen-selfballoon.c b/drivers/xen/xen-selfballoon.c index 6ea852e..e3e48f1 100644 --- a/drivers/xen/xen-selfballoon.c +++ b/drivers/xen/xen-selfballoon.c @@ -195,14 +195,13 @@ __setup("selfballooning", xen_selfballooning_setup); */ static void selfballoon_process(struct work_struct *work) { - unsigned long cur_pages, goal_pages, tgt_pages; + unsigned long cur_pages, goal_pages, tgt_pages, floor_pages; bool reset_timer = false; if (xen_selfballooning_enabled) { - cur_pages = balloon_stats.current_pages; + cur_pages = totalram_pages; tgt_pages = cur_pages; /* default is no change */ - goal_pages = percpu_counter_read_positive(&vm_committed_as) + - balloon_stats.current_pages - totalram_pages; + goal_pages = percpu_counter_read_positive(&vm_committed_as); #ifdef CONFIG_FRONTSWAP /* allow space for frontswap pages to be repatriated */ if (frontswap_selfshrinking && frontswap_enabled) @@ -217,7 +216,13 @@ static void selfballoon_process(struct work_struct *work) ((goal_pages - cur_pages) / selfballoon_uphysteresis); /* else if cur_pages == goal_pages, no change */ - balloon_set_new_target(tgt_pages); + floor_pages = totalreserve_pages + + (roundup_pow_of_two(max_pfn) >> 5); + /* don''t balloon too far, lest OOMs occur... */ + if (tgt_pages < floor_pages) + tgt_pages = floor_pages; + balloon_set_new_target(tgt_pages + + balloon_stats.current_pages - totalram_pages); reset_timer = true; } #ifdef CONFIG_FRONTSWAP _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Konrad Rzeszutek Wilk
2011-Sep-26 17:23 UTC
[Xen-devel] Re: [PATCH] xen: Fix selfballooning and ensure it doesn''t go too far
On Sat, Sep 24, 2011 at 01:58:08PM -0700, Dan Magenheimer wrote:> [PATCH] xen: Fix selfballooning and ensure it doesn''t go too far > > The balloon driver''s "current_pages" is very different from > totalram_pages. Self-ballooning needs to be driven by > the latter. Also, Committed_AS doesn''t account for pages > used by the kernel so enforce a floor for when there > are little or no user-space threads using memory.Hey Dan, ..> + floor_pages = totalreserve_pages + > + (roundup_pow_of_two(max_pfn) >> 5);Would it make sense to make the shift be a runtime argument in case some users report problems with that calculation?> + /* don''t balloon too far, lest OOMs occur... */ > + if (tgt_pages < floor_pages) > + tgt_pages = floor_pages; > + balloon_set_new_target(tgt_pages + > + balloon_stats.current_pages - totalram_pages); > reset_timer = true; > } > #ifdef CONFIG_FRONTSWAPOtherwise it looks OK to me. Would you like me to queue it up for 3.1-rc7? _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Dan Magenheimer
2011-Sep-26 17:24 UTC
[Xen-devel] RE: [PATCH] xen: Fix selfballooning and ensure it doesn''t go too far
> From: Konrad Rzeszutek Wilk > Sent: Monday, September 26, 2011 11:23 AM > To: Dan Magenheimer > Cc: linux-kernel@vger.kernel.org; xen-devel@lists.xensource.com; David Vrabel; Jeremy Fitzhardinge > Subject: Re: [PATCH] xen: Fix selfballooning and ensure it doesn''t go too far > > On Sat, Sep 24, 2011 at 01:58:08PM -0700, Dan Magenheimer wrote: > > [PATCH] xen: Fix selfballooning and ensure it doesn''t go too far > > > > The balloon driver''s "current_pages" is very different from > > totalram_pages. Self-ballooning needs to be driven by > > the latter. Also, Committed_AS doesn''t account for pages > > used by the kernel so enforce a floor for when there > > are little or no user-space threads using memory. > > Hey Dan, > .. > > + floor_pages = totalreserve_pages + > > + (roundup_pow_of_two(max_pfn) >> 5); > > Would it make sense to make the shift be a runtime argument > in case some users report problems with that calculation?Good idea. I''ll take a look at that.> > + /* don''t balloon too far, lest OOMs occur... */ > > + if (tgt_pages < floor_pages) > > + tgt_pages = floor_pages; > > + balloon_set_new_target(tgt_pages + > > + balloon_stats.current_pages - totalram_pages); > > reset_timer = true; > > } > > #ifdef CONFIG_FRONTSWAP > > Otherwise it looks OK to me. Would you like me to queue it up > for 3.1-rc7?Will let you know when I have that change done/tested. Thanks, Dan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel